The Icelandic eruption that caused travel misery for millions of airline passengers in April could be just a hiccup compared with the potential impact of a bigger eruption, an Icelandic expert has warned.

At its peak in mid-April, the Eyjafjallajökull volcano caused the cancellation of more than 100,000 flights, affecting eight million passengers. But there could be worse to come, vulcanologist Haraldur Sigurdsson told a conference to discuss how to improve coordination of the global response to another eruption. Each of the eruptions of Eyjafjallajökull in 920, 1612, and 1821-1823 was followed by an eruption of its larger neighbour Katla. If the same thing happens this time, Katla is likely to send up massive plumes of ash.

Nancy Graham, the director of the International Civil Aviation Organisation, called for new scientific standards to judge whether air space closure is necessary. Other speakers stressed the need for clear decision making if there is another eruption, calling for a ‘single European sky’ with air traffic in the whole of European airspace controlled by a single body.

While there isn’t much anyone can do about volcanic eruptions, it does make sense to check your travel insurance policy to see if it covers flight cancellations through volcanic activity.